The invention relates to an injection system for an internal combustion engine operating on self-igniting liquefied petroleum gas and including at least one injector per cylinder for direct fuel injection into the combustion chamber, with a fuel tank in which fuel is held at a freed pressure, and a high-pressure fuel pump delivering fuel to the injector, and a shutdown device enabling connection of pressurized parts of the injection system to the fuel tank by way of at least one pressure relief line.